In general, tranexamic acid functions as a hemostatic agent when orally taken, and also functions as an anticoagulant agent, an anti-allergic agent, or an anti-inflammatory agent when topically applied. Tranexamic acid is used as ethical drugs and is also blended in OTC drugs. Owing to its effects on hyperpigmentation such as melasma, tranexamic acid is used for the treatment of hyperpigmentation and for whitening.
Meanwhile, it has been noted that tranexamic acid has many problems in terms of sense of use, skin irritation, storage stability, and skin permeation, when used as an agent for external use. For example, Korean Patent No. 1087602 indicates a problem that a low-viscosity liquid composition blended with tranexamic acid leaves sticky or thick feeling when applied to the skin, and in particular, the feeling is remarkably increased when more than 0.5% by weight of tranexamic acid is used. Further, Korean Patent No. 1159574 indicates a problem that due to high crystallinity of tranexamic acid, crystals are precipitated in a tranexamic acid-blended agent for external use with evaporation over time. Furthermore, Japanese Patent Publication No. 2010-229100 indicates a problem that tranexamic acid shows very low skin permeability when applied to the skin.
Moreover, the present inventors have analyzed various commercial agents for external use including tranexamic acid as an active ingredient, and as a result, they found that tranexamic acid included in the commercial products does not permeate the human skin in an in-vitro transdermal permeability test (see Experimental Example 1).